Bionomics of Tetrastichus giffardianus (Hymenoptera: Eulophidae): An Endoparasitoid of Tephritid Fruit Flies

Abstract

Tetrastichus giffardianus Silvestri is a gregarious endoparasitoid of tephritid fruit flies in Hawaii. Although widely established in Hawaii, it has been largely overlooked in field surveys. Our objectives were to develop an efficient rearing technique for T. giffardianus , and to determine basic bionomic and demographic parameters, necessary in future augmentative and/or classical biological control programs. Exposure of 5- and 6-d-old Ceratitis capitata (Weidemann) larvae to parasitoids at a 5:1 host:parasitoid ratio resulted in relatively high parasitism rates (>55%). Increasing exposure times to parasitoids for ≥8 h did not reduced emergence rates. T. giffardianus successfully developed in Bactrocera dorsalis (Hendel), B. latifrons (Hendel), B. cucurbitae (Coquillet) and C. capitata . Parasitism was highest in B. dorsalis (37%) and lowest in B. cucurbitae (5%). The longevity of ovipositing females was 60% lower than females deprived of hosts. Each female parasitized 9.1 C. capitata larvae in her lifetime and 0.8 ± 0.13 larvae were parasitized per day. At 26°C, gross and net reproductive rates were 57.3 and 42.6 progeny per female per day, respectively. Peak parasitism of hosts occurred in 2-d old females, followed by a 2nd peak in 6- to 8-d-old females. The significance of T. giffardianus to biological control of tephritids is discussed.